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Greater Boston | Is Autism Genetic or Environmental?

Conflicting theories about what causes autism are explored in this video segment from Greater Boston. Scientists still don’t have an answer, and while many focus on genetics, some suspect that environment may also play a role. Mark Blaxill, whose daughter Michaela is autistic, explains why he thinks the disorder is triggered by environmental factors. Dr. Martha Herbert, who studies the brains of autistic children, says that toxins like metals, pesticides, and PCBs have all come under suspicion. But other scientists, like Dr. David Miller, say the key to autism lies in a person’s genes.

Autism is a developmental disorder that affects social and communication skills. A person with autism may have trouble making friends, having a conversation, or even talking. In fact, about 40 percent of people with autism never speak. The symptoms of autism can range from mild to severe; autism is part of a group of developmental disabilities known as autism spectrum disorders (ASD).

The symptoms of ASD appear in early childhood, before the age of three. To parents, a child’s diagnosis of autism can be devastating, and it’s natural to look for causes. Unfortunately, as yet, there are no easy explanations. Autism has no single, known cause. Since the disorder is complex and no two children with autism are alike, experts suspect that the disorder may have several causes. These include genetic problems and environmental factors, such as diet or contaminants in food or water.

Genetics is probably a significant factor. Autism tends to run in families; a child with parents or siblings with autism is more likely to have it as well. Scientists are trying to pinpoint exactly which genes may be responsible for autism. A number of genetic problems appear to be involved, including chromosome abnormalities—extra, missing, or rearranged chromosomes—as well as alterations in a single gene.

Because autism strikes children from all races, locations, and socioeconomic levels, researchers are also studying whether certain environmental factors that affect wide swaths of the population—such as viral infections, air pollutants, pesticides, or exposure to heavy metals—may be triggering autism. It is known that exposure to certain substances in the womb can have an effect: if a pregnant woman has a certain type of infection, like rubella, or takes certain medications, like thalidomide, her child will have a higher risk of being autistic.

There was significant controversy in recent years over a possible link between autism and vaccines, however, additional studies have shown that there is no link. In particular, one study published in 1998 theorized that there could be a link between the MMR (measles, mumps, and rubella) vaccination and autism. That study has since been retracted by the journal that published it after a review board determined the author of the study had been both fraudulent and irresponsible in his research.

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